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BKDR_POISON.BSJ

June 07, 2013
 ALIASES:

Win32/Agent.BB (AVG), Backdoor.Win32.Poison.fttf (Kaspersky), VirTool:Win32/DelfInject.gen!BO (Microsoft)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It connects to a website to send and receive information.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

36,864 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 May 2013

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This backdoor stays memory-resident by creating remote threads:

  • %Windows%\explorer.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKLM\SOFTWARE\Microsoft\
Active Setup\Installed Components\{A5184084-E6E4-89F4-B092-538C1B1EB0AE}
StubPath = "%System%:SMAX4NP.exe"

Backdoor Routine

This backdoor connects to the following websites to send and receive information:

  • {BLOCKED}3.{BLOCKED}account.org

Other Details

This backdoor deletes the initially executed copy of itself

NOTES:

This backdoor creates an Alternate Data Stream (ADS) copy of itself:

  • %System%:SMAX4NP.exe

This allows the malware to hide itself from detection. It also allows it to execute whenever the Windows system folder is accessed.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.948.04

FIRST VSAPI PATTERN DATE:

29 May 2013

VSAPI OPR PATTERN File:

9.949.00

VSAPI OPR PATTERN Date:

30 May 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{A5184084-E6E4-89F4-B092-538C1B1EB0AE}
    • StubPath = "%System%:SMAX4NP.exe"

Step 4

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_POISON.BSJ. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 5

To delete ADS files:

  1. Download Streams.exe from this Microsoft page.
  2. Extract the contents of this file to a location of your choice.
  3. Open a command prompt window. To do this:
    • On Windows 2000, XP, and Server 2003:
      Click Start>Run. In the input box, type CMD, and press Enter.
    • On Windows Vista and 7:
      Click the Windows button, type CMD in the search box, and press Enter.
  4. In the command prompt, type the following, then press Enter:
    CD {Path where contents of downloaded file was extracted}
  5. Still in the command prompt type the following then press Enter:
    Streams.exe -d %System%
  6. Type exit then press Enter.

NOTES:

Step 5:

To delete ADS files:

Download Streams.exe from this Microsoft page.

Extract the contents of this file to a location of your choice.

Open a command prompt window. To do this:

On Windows 2000, XP, and Server 2003:

Click Start > Run. In the input box, type CMD, and press Enter. On Windows Vista and 7:

Click the Windows button, type CMD in the search box, and press Enter.

In the command prompt, type the following, then press Enter:

  • CD {Path where contents of downloaded file was extracted}

Still in the command prompt type the following then press Enter:

  • Streams.exe -d %System%:SMAX4NP.exe

Type exit then press Enter.


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